The potential of emerging bio-based products to reduce environmental impacts

The current debate on the sustainability of bio-based products questions the environmental benefits of replacing fossil- by bio-resources. Here, we analyze the environmental trade-offs of 98 emerging bio-based materials compared to their fossil counterparts, reported in 130 studies. Although greenhouse gas life cycle emissions for emerging bio-based products are on average 45% lower (−52 to −37%; 95% confidence interval), we found a large variation between individual bio-based products with none of them reaching net-zero emissions. Grouped in product categories, reductions in greenhouse gas emissions ranged from 19% (−52 to 35%) for bioadhesives to 73% (−84 to −54%) for biorefinery products. In terms of other environmental impacts, we found evidence for an increase in eutrophication (369%; 163 to 737%), indicating that environmental trade-offs should not be overlooked. Our findings imply that the environmental sustainability of bio-based products should be evaluated on an individual product basis and that more radical product developments are required to reach climate-neutral targets.


Arithmetic average
The ratio of the sum to the total number Predicted mean The mean calculated by running LMM

S.1 Methods: Decision Trees
The screening and inclusion of prospective LCAs followed two criteria.For the first criteria, we followed the decision tree in

S.5 Predicted mean reduction (RR) and 95% CI for GHG emissions per product category, feedstock category and TRL based on single linear mixed-effect models
S.10 Overview of the predicted mean and 95% CI of the RRs across all product types and studies for all environmental impacts with n ≤ 30.Separate random-effects models were ran for each impact category.
Figure S.1.1 on the scope, quality and clarity of the study.For the second criteria, we followed the decision tree in Figure S.1.2.

Figure S. 1 . 1 :
Figure S.1.1:Decisiontree study selection related to the scope of the study.Furthermore, if the quality and/or clarity was lacking the study had to be excluded as well.

S. 6
Predicted mean RR and 95% CI for the GHG emissions and if it in-or excluded Land Use Changes (LUC) related GHG emissions based on single linear mixed-effect models.

Figure S. 10 :
Figure S.10: plot showing predicted mean and 95% CI of the other environmental impacts' RRs (with n ≤ 30) collected from the 130 studies (Human Ecotoxicity, Freshwater Ecotoxicity, Marine Aquatic Ecotoxicity, Land Use, Water Scarcity, Depletion of Abiotic Resources).

.2 Methods: Overview TRLs
Figure S.1.2:Decision tree on products to include in the comparative assessment.The bio-based product is a 'drop-in' of a fossilbased product, meaning it has the same chemical structure, or it can be compared to a fossil-based product which has the same function

Table S . 3
: overview of the bio-based products, the number of data points (n), the arithmetic average RR and 95% CI; if n = 1, there is no 95% CI, which is indicated with 0; *indicates the bio-based product with their average and 95% CI below zero.

Additional calculations in 'Greenhouse gas Footprints' Table S.4: additional
GHG emission calculations in the section 'Greenhouse gas Footprints'.

Table S . 5 :
Change in GHG footprint response ratios (RR) of bio-based products in comparison to fossil-based counterfactual in relation to key parameters: product category, feedstock category and TRL category (corresponding to Fig.2in the main text).